Java ThreadGroup parentOf()用法及代码示例

ThreadGroup类parentOf()方法

• parentOf() 方法在 java.lang 包中可用。
• parentOf() 方法用于检查给定线程组或其任何祖先的线程组是否是该线程组。
• parentOf() 方法是一个非静态方法，它只能通过类对象访问，如果我们尝试使用类名访问方法，那么我们将得到一个错误。
• parentOf() 方法在检查父线程组时不抛出异常。

用法:

    public final boolean parentOf(ThreadGroup tg);

参数：

• ThreadGroup tg– 代表线程组。

返回值：

这个方法的返回类型是Boolean– 当给定的线程组或其任何祖先的线程组是该线程组时返回真，否则返回假。

例：

// Java program to demonstrate the example 
// of boolean parentOf(ThreadGroup tg) method of ThreadGroup 

public class ParentOf implements Runnable {
    public static void main(String[] args) {
        ParentOf p = new ParentOf();
        p.parent();
    }

    public void parent() {
        try {
            // Create two thread group and the named are base
            // and derived

            ThreadGroup base = new ThreadGroup("Base ThreadGroup");
            ThreadGroup derived = new ThreadGroup(base, "Derived ThreadGroup");

            // create two threads
            Thread th1 = new Thread(base, this);
            Thread th2 = new Thread(derived, this);

            // By using getName() method is to retrieve the
            // name of the thread th1
            System.out.println(th1.getName() + " " + "begins.....");

            // By using start() method is to start its execution 
            // of thread th1
            th1.start();

            //By using getName() method is to retrieve the
            // name of the thread th2
            System.out.println(th2.getName() + " " + "begins.....");
            th2.setPriority(10);

            // By using start() method is to start its execution 
            // of thread th2
            th2.start();

            // By using parentOf() method is to
            // check the parent status of
            // the thread group
            boolean b1 = base.parentOf(derived);
            boolean b2 = derived.parentOf(base);

            System.out.println("Is" + " " + base.getName() + " " + "parent of derived:" + " " + b1);
            System.out.println("Is" + " " + derived.getName() + " " + "parent of base:" + " " + b2);

            // By using join() method is to wait the current
            // thread till complete execution of another thread
            th1.join();
            th2.join();
        } catch (InterruptedException ex) {
            ex.printStackTrace();
        }
    }

    // Override run()
    public void run() {
        for (int k = 0; k < 100; ++k)
            ++k;
        System.out.println(Thread.currentThread().getName() + " " + "ends.....");
    }
}

输出

Thread-0 begins.....
Thread-1 begins.....
Thread-0 ends.....
Thread-1 ends.....
Is Base ThreadGroup parent of derived:true
Is Derived ThreadGroup parent of base:false